Method for limited positioning-based reporting in wireless communication system and apparatus therefor

ABSTRACT

Provided is a method for reporting by a terminal in a wireless communication system. The method comprises: receiving positioning-limiting information from a network; and determining whether to allow positioning on the basis of the positioning limiting information. The method additionally comprises, if the positioning is allowed, acquiring location information by means of positioning, and reporting the location information via a network.

This application is a National Stage Application of International PatentApplication No. PCT/KR2013/000710, filed on Jan. 29, 2013, and claimsthe benefit of U.S. Provisional Application No. 61/591,992, filed onJan. 29, 2012 in the United States Patent and Trademark Office, all ofwhich are incorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to wireless communication and, moreparticularly, to a report method based on restricted positioning in awireless communication system and an apparatus for supporting the same.

2. Related Art

3rd generation partnership project (3GPP) long term evolution (LTE) isan improved version of a universal mobile telecommunication system(UMTS) and is introduced as the 3GPP release 8. The 3GPP LTE usesorthogonal frequency division multiple access (OFDMA) in a downlink, anduses single carrier-frequency division multiple access (SC-FDMA) in anuplink. The 3GPP LTE employs multiple input multiple output (MIMO)having up to four antennas. In recent years, there is an ongoingdiscussion on 3GPP LTE-advanced (LTE-A) that is an evolution of the 3GPPLTE.

A Minimization of Driving Tests (MDT) is that operators perform testsusing UE instead of vehicles for coverage optimization purposes.Coverage varies depending on the location of a BS, the deployment ofsurrounding buildings, and environments used by users. Accordingly, anoperator needs to periodically perform driving tests, and great expenseand lots of resources are required. The MDT is that an operator measurescoverage using UE.

An MDT may be divided into a logged MDT and an immediate MDT. Inaccordance with the logged MDT, UE performs MDT measurements, and thentransfers logged measurements to a network at a specific time point. Inaccordance with the immediate MDT, UE performs MDT measurements, andthen transfers logged measurements to a network when report conditionsare satisfied. In the logged MDT, the logging of measured results may belimited to logging the measured results according to measurementsperformed in RRC idle mode. The logged measurements may be used in RRCconnected mode in response to a command from a network. In accordancewith the immediate MDT, UE may perform MDT measurements in RRC connectedmode.

Assuming that the primary object of the MDT is coverage optimization, UEpreferably reports information related to the location where measuredresults have been obtained along with the corresponding measuredresults. Accordingly, a network may configure the MDT for only UEcapable of providing location information, and may perform aconfiguration so that corresponding measured results are reported.

If UE reports information about the location of unrestricted coveragealthough location information desired to be collected by a network isrestricted to a specific time zone or a specific network area, thenetwork receives excessively obtained location information, therebyincreasing overhead. Furthermore, there may be a problem in that poweris unnecessarily consumed because UE performs positioning in order toobtain location information having a low importance. Accordingly, thereis a need for a report method based on restricted positioning, whereinlocation information is more efficiently collected and used in networkoperations.

SUMMARY OF THE INVENTION

The present invention provides a report method based on restrictedpositioning in a wireless communication system and an apparatus forsupporting the same.

In an aspect, there is provided a report method by UE in a wirelesscommunication system. The method includes receiving positioningrestriction information from a network and determining whether or notpositioning has been permitted based on the positioning restrictioninformation. The method further includes obtaining location informationby performing the positioning, if the positioning has been permitted,and reporting the location information to the network.

The positioning restriction information may be configured to beindicative of the start time point and the end time point of a timeinterval in which the positioning of the user equipment has beenpermitted.

Determining whether or not the positioning has been permitted mayinclude determining that the execution of the positioning has beenpermitted if a time point at which the user equipment operates isbetween the start time point and the end time point.

The positioning restriction information may be configured to beindicative of the length of the time interval in which the positioningof the user equipment may be permitted. The method may further includestarting a restriction timer set to the length, indicated by thepositioning restriction information, when the positioning restrictioninformation may be received.

Determining whether or not the positioning has been permitted mayinclude determining that the execution of the positioning has beenpermitted if the restriction timer is being driven.

The positioning restriction information may be indicative of coverage inwhich the positioning has been permitted.

The coverage in which the positioning has been permitted may be at leastone cell. The positioning restriction information may include a celllist indicative of the at least one cell.

Determining whether or not the positioning has been permitted mayinclude determining that the execution of the positioning has beenpermitted if the serving cell of the user equipment is indicated by thecell list.

The coverage in which the positioning is permitted may be at least onefrequency. The positioning restriction information may include afrequency list indicative of the at least one frequency.

Determining whether or not the positioning has been permitted mayinclude determining that the execution of the positioning has beenpermitted if the operation frequency of the serving cell of the userequipment is indicated by the frequency list.

The positioning restriction information may be included in a loggedmeasurement configuration including configuration information for alogged Minimization Driving Test (MDT), and may be transmitted.

The method may further include entering a Radio Resource Control (RRC)idle state and performing measurement on a serving cell and/or at leastone neighbor cell based on the logged measurement configuration.Obtaining the location information may be performed in the RRC idlestate.

The method may further include logging the results of the measurementand the location information if the positioning may be permitted.Reporting the location information to the network may include reportinga report message, including the logged measured results and locationinformation, to the network.

The method may further include logging the results of the measurement ifthe positioning is not permitted and reporting the report message,including the logged measured results, to the network.

In another aspect, there is provided a wireless apparatus operating in awireless communication system operation. The wireless apparatus includesa Radio Frequency (RF) unit that sends and receives radio signals and aprocessor that may be functionally coupled to the RF unit and operates.The processor is configured to receive positioning restrictioninformation from a network and to determine whether or not positioninghas been permitted based on the positioning restriction information. Theprocessor is further configured to obtain location information byperforming the positioning if the positioning has been permitted andreport the location information to the network.

In accordance with an embodiment of the present invention, a network canrestrict positioning so that UE performs positioning only in a specifictime interval or a specific network area. Accordingly, the network canobtain location information in the time and place at which locationinformation obtained through positioning may be more usefully used. Incontrast, the network can restrict a report on location information inthe time and area at which the importance of location information isrelatively low, thereby being capable of reducing overhead. Through suchselective collection of location information, network optimization canbe more efficiently performed, and the performance of a wirelesscommunication system can be further improved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a wireless communication system to which the presentinvention is applied.

FIG. 2 is a block diagram showing the structure of a wireless protocolon the user plane.

FIG. 3 is a block diagram showing the structure of a wireless protocolon the control plane.

FIG. 4 is a flowchart illustrating the operation of UE in the RRC idlestate.

FIG. 5 is a flowchart illustrating a process of establishing RRCconnection.

FIG. 6 is a flowchart illustrating an RRC connection reconfigurationprocess.

FIG. 7 is a diagram illustrating an RRC connection re-establishmentprocedure.

FIG. 8 is a flowchart illustrating a method of performing measurement.

FIG. 9 illustrates an example of a measurement configuration configuredto UE.

FIG. 10 illustrates an example in which a measurement identity isdeleted.

FIG. 11 illustrates an example in which a measurement object is deleted.

FIG. 12 is a flowchart illustrating a method of performing a logged MDT.

FIG. 13 is a diagram illustrating an example of a logged MDT accordingto a logged area.

FIG. 14 is a diagram illustrating an example of a logged MDT accordingto a change of RAT.

FIG. 15 is a diagram illustrating an example of logged measurements.

FIG. 16 is a diagram illustrating an example of an immediate MDT.

FIG. 17 is a diagram illustrating an example of the structure of awireless communication system to which the positioning of UE is appliedaccording to an embodiment of the present invention.

FIG. 18 is a diagram illustrating overall procedures for locationservice according to an embodiment of the present invention.

FIG. 19 is a diagram illustrating a report method based on positioningrestriction according to an embodiment of the present invention.

FIG. 20 is a flowchart illustrating an example of a report method basedon restricted positioning according to an embodiment of the presentinvention.

FIG. 21 is a flowchart illustrating another example of a report methodbased on restricted positioning according to an embodiment of thepresent invention.

FIG. 22 is a flowchart illustrating yet another example of a reportmethod based on restricted positioning according to an embodiment of thepresent invention.

FIG. 23 is a block diagram illustrating a wireless apparatus in which anembodiment of the present invention is implemented.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

FIG. 1 shows a wireless communication system to which the presentinvention is applied. The wireless communication system may also bereferred to as an evolved-UMTS terrestrial radio access network(E-UTRAN) or a long term evolution (LTE)/LTE-A system.

The E-UTRAN includes at least one base station (BS) 20 which provides acontrol plane and a user plane to a user equipment (UE) 10. The UE 10may be fixed or mobile, and may be referred to as another terminology,such as a mobile station (MS), a user terminal (UT), a subscriberstation (SS), a mobile terminal (MT), a wireless device, etc. The BS 20is generally a fixed station that communicates with the UE 10 and may bereferred to as another terminology, such as an evolved node-B (eNB), abase transceiver system (BTS), an access point, etc.

The BSs 20 are interconnected by means of an X2 interface. The BSs 20are also connected by means of an S1 interface to an evolved packet core(EPC) 30, more specifically, to a mobility management entity (MME)through S1-MME and to a serving gateway (S-GW) through S1-U.

The EPC 30 includes an MME, an S-GW, and a packet data network-gateway(P-GW). The MME has access information of the UE or capabilityinformation of the UE, and such information is generally used formobility management of the UE. The S-GW is a gateway having an E-UTRANas an end point. The P-GW is a gateway having a PDN as an end point.

Layers of a radio interface protocol between the UE and the network canbe classified into a first layer (L1), a second layer (L2), and a thirdlayer (L3) based on the lower three layers of the open systeminterconnection (OSI) model that is well-known in the communicationsystem. Among them, a physical (PHY) layer belonging to the first layerprovides an information transfer service by using a physical channel,and a radio resource control (RRC) layer belonging to the third layerserves to control a radio resource between the UE and the network. Forthis, the RRC layer exchanges an RRC message between the UE and the BS.

FIG. 2 is a diagram showing a wireless protocol architecture for a userplane. FIG. 3 is a diagram showing a wireless protocol architecture fora control plane. The user plane is a protocol stack for user datatransmission. The control plane is a protocol stack for control signaltransmission.

Referring to FIGS. 2 and 3, a PHY layer provides an upper layer with aninformation transfer service through a physical channel. The PHY layeris connected to a medium access control (MAC) layer which is an upperlayer of the PHY layer through a transport channel. Data is transferredbetween the MAC layer and the PHY layer through the transport channel.The transport channel is classified according to how and with whatcharacteristics data is transferred through a radio interface.

Data is moved between different PHY layers, that is, the PHY layers of atransmitter and a receiver, through a physical channel. The physicalchannel may be modulated according to an Orthogonal Frequency DivisionMultiplexing (OFDM) scheme, and use the time and frequency as radioresources.

The functions of the MAC layer include mapping between a logical channeland a transport channel and multiplexing and demultiplexing to atransport block that is provided through a physical channel on thetransport channel of a MAC Service Data Unit (SDU) that belongs to alogical channel. The MAC layer provides service to a Radio Link Control(RLC) layer through the logical channel.

The functions of the RLC layer include the concatenation, segmentation,and reassembly of an RLC SDU. In order to guarantee various types ofQuality of Service (QoS) required by a Radio Bearer (RB), the RLC layerprovides three types of operation mode: Transparent Mode (TM),Unacknowledged Mode (UM), and Acknowledged Mode (AM). AM RLC provideserror correction through an Automatic Repeat Request (ARQ).

The RRC layer is defined only on the control plane. The RRC layer isrelated to the configuration, reconfiguration, and release of radiobearers, and is responsible for control of logical channels, transportchannels, and PHY channels. An RB means a logical route that is providedby the first layer (PHY layer) and the second layers (MAC layer, the RLClayer, and the PDCP layer) in order to transfer data between UE and anetwork.

The function of a Packet Data Convergence Protocol (PDCP) layer on theuser plane includes the transfer of user data and header compression andciphering. The function of the PDCP layer on the user plane furtherincludes the transfer and encryption/integrity protection of controlplane data.

What an RB is configured means a process of defining the characteristicsof a wireless protocol layer and channels in order to provide specificservice and configuring each detailed parameter and operating method. AnRB can be divided into two types of a Signaling RB (SRB) and a Data RB(DRB). The SRB is used as a passage through which an RRC message istransmitted on the control plane, and the DRB is used as a passagethrough which user data is transmitted on the user plane.

If RRC connection is established between the RRC layer of UE and the RRClayer of an E-UTRAN, the UE is in the RRC connected state. If not, theUE is in the RRC idle state.

A downlink transport channel through which data is transmitted from anetwork to UE includes a broadcast channel (BCH) through which systeminformation is transmitted and a downlink shared channel (SCH) throughwhich user traffic or control messages are transmitted. Traffic or acontrol message for downlink multicast or broadcast service may betransmitted through the downlink SCH, or may be transmitted through anadditional downlink multicast channel (MCH). Meanwhile, an uplinktransport channel through which data is transmitted from UE to a networkincludes a random access channel (RACH) through which an initial controlmessage is transmitted and an uplink shared channel (SCH) through whichuser traffic or control messages are transmitted.

Logical channels that are placed over the transport channel and that aremapped to the transport channel include a broadcast control channel(BCCH), a paging control channel (PCCH), a common control channel(CCCH), a multicast control channel (MCCH), and a multicast trafficchannel (MTCH).

The physical channel includes several OFDM symbols in the time domainand several subcarriers in the frequency domain. One subframe includes aplurality of OFDM symbols in the time domain. An RB is a resourcesallocation unit, and includes a plurality of OFDM symbols and aplurality of subcarriers. Furthermore, each subframe may use specificsubcarriers of specific OFDM symbols (e.g., the first OFDM symbol) ofthe corresponding subframe for a physical downlink control channel(PDCCH), that is, an L1/L2 control channel. A Transmission Time Interval(TTI) is a unit time for subframe transmission.

The RRC state of UE and an RRC connection method are described below.

The RRC state means whether or not the RRC layer of UE is logicallyconnected to the RRC layer of the E-UTRAN. A case where the RRC layer ofUE is logically connected to the RRC layer of the E-UTRAN is referred toas an RRC connected state. A case where the RRC layer of UE is notlogically connected to the RRC layer of the E-UTRAN is referred to as anRRC idle state. The E-UTRAN may check the existence of corresponding UEin the RRC connected state in each cell because the UE has RRCconnection, so the UE may be effectively controlled. In contrast, theE-UTRAN is unable to check UE in the RRC idle state, and a Core Network(CN) manages UE in the RRC idle state in each tracking area, that is,the unit of an area greater than a cell. That is, the existence ornon-existence of UE in the RRC idle state is checked only for each largearea. Accordingly, the UE needs to shift to the RRC connected state inorder to be provided with common mobile communication service, such asvoice or data.

When a user first powers UE, the UE first searches for a proper cell andremains in the RRC idle state in the corresponding cell. The UE in theRRC idle state establishes RRC connection with an E-UTRAN through an RRCconnection procedure when it is necessary to set up the RRC connection,and shifts to the RRC connected state. A case where UE in the RRC idlestate needs to set up RRC connection includes several cases. Forexample, the cases may include a need to send uplink data for a reason,such as a call attempt by a user, and to send a response message as aresponse to a paging message received from an E-UTRAN.

A Non-Access Stratum (NAS) layer placed over the RRC layer performsfunctions, such as session management and mobility management.

In the NAS layer, in order to manage the mobility of UE, two types ofstates: EPS Mobility Management-REGISTERED (EMM-REGISTERED) andEMM-DEREGISTERED are defined. The two states are applied to UE and theMME. UE is initially in the EMM-DEREGISTERED state. In order to access anetwork, the UE performs a process of registering it with thecorresponding network through an initial attach procedure. If the attachprocedure is successfully performed, the UE and the MME become theEMM-REGISTERED state.

In order to manage signaling connection between UE and the EPC, twotypes of states: an EPS Connection Management (ECM)-IDLE state and anECM-CONNECTED state are defined. The two states are applied to UE andthe MME. When the UE in the ECM-IDLE state establishes RRC connectionwith the E-UTRAN, the UE becomes the ECM-CONNECTED state. The MME in theECM-IDLE state becomes the ECM-CONNECTED state when it establishes S1connection with the E-UTRAN. When the UE is in the ECM-IDLE state, theE-UTRAN does not have information about the context of the UE.Accordingly, the UE in the ECM-IDLE state performs procedures related toUE-based mobility, such as cell selection or cell reselection, without aneed to receive a command from a network. In contrast, when the UE is inthe ECM-CONNECTED state, the mobility of the UE is managed in responseto a command from a network. If the location of the UE in the ECM-IDLEstate is different from a location known to the network, the UE informsthe network of its corresponding location through a tracking area updateprocedure.

System information is described below.

System information includes essential information that needs to be knownby UE in order for the UE to access a BS. Accordingly, the UE needs tohave received all pieces of system information before accessing the BS,and needs to always have the up-to-date system information. Furthermore,the BS periodically transmits the system information because the systeminformation is information that needs to be known by all UEs within onecell.

In accordance with Paragraph 5.2.2 of 3GPP TS 36.331 V8.7.0 (2009-09)“Radio Resource Control (RRC); Protocol specification (Release 8)”, thesystem information is classified into a Master Information Block (MIB),a Scheduling Block (SB), and a System Information Block (SIB). The MIBinforms UE of the physical configuration of a corresponding cell, forexample, a bandwidth. The SB informs UE of information about thetransmission of SIBs, for example, a transmission cycle. The SIB is aset of pieces of correlated system information. For example, a specificSIB includes only information about surrounding cells, and a specificSIB includes only information about an uplink radio channel used by UE.

In general, service that is provided to UE by a network may beclassified into three types as follows. Furthermore, the UE differentlyrecognizes the type of cell depending on what service may be provided tothe UE. In the following description, a service type is first described,and the type of cell is described.

1) Limited service: this service provides emergency calls and anEarthquake and Tsunami Warning System (ETWS), and may be provided by anacceptable cell.

2) Suitable service: this service means public service for common uses,and may be provided by a suitable cell (or a normal cell).

3) Operator service: this service means service for communicationnetwork operators. This cell may be used by only communication networkoperators, but may not be used by common users.

In relation to a service type provided by a cell, the type of cell maybe classified as follows.

1) An acceptable cell: this cell is a cell from which UE may be providedwith limited service. This cell is a cell that has not been barred froma viewpoint of corresponding UE and that satisfies the cell selectioncriterion of the UE.

2) A suitable cell: this cell is a cell from which UE may be providedwith suitable service. This cell satisfies the conditions of anacceptable cell and also satisfies additional conditions. The additionalconditions include that the suitable cell needs to belong to a PublicLand Mobile Network (PLMN) to which corresponding UE may access and thatthe suitable cell is a cell on which the execution of a tracking areaupdate procedure by the UE is not barred. If a corresponding cell is aCSG cell, the cell needs to be a cell to which UE may access as a memberof the CSG.

3) A barred cell: this cell is a cell that broadcasts informationindicative of a barred cell through system information.

4) A reserved cell: this cell is a cell that broadcasts informationindicative of a reserved cell through system information.

FIG. 4 is a flowchart illustrating the operation of UE in the RRC idlestate. FIG. 4 illustrates a procedure in which UE that is initiallypowered on experiences a cell selection process, registers it with anetwork, and then performs cell reselection if necessary.

Referring to FIG. 4, the UE selects Radio Access Technology (RAT) inwhich the UE communicates with a Public Land Mobile Network (PLMN), thatis, a network from which the UE is provided with service (S410).Information about the PLMN and the RAT may be selected by the user ofthe UE, and the information stored in a Universal Subscriber IdentityModule (USIM) may be used.

The UE selects a cell that has the greatest value and that belongs tocells having measured BS and signal intensity or quality greater than aspecific value (cell selection) (S420). In this case, the UE that ispowered off performs cell selection, which may be called initial cellselection. A cell selection procedure is described later in detail.After the cell selection, the UE receives system informationperiodically by the BS. The specific value refers to a value that isdefined in a system in order for the quality of a physical signal indata transmission/reception to be guaranteed. Accordingly, the specificvalue may differ depending on applied RAT.

If network registration is necessary, the UE performs a networkregistration procedure (S430). The UE registers its information (e.g.,an IMSI) with the network in order to receive service (e.g., paging)from the network. The UE does not register it with a network whenever itselects a cell, but registers it with a network when information aboutthe network (e.g., a Tracking Area Identity (TAI)) included in systeminformation is different from information about the network that isknown to the UE.

The UE performs cell reselection based on a service environment providedby the cell or the environment of the UE (S440). If the value of theintensity or quality of a signal measured based on a BS from which theUE is provided with service is lower than that measured based on a BS ofa neighboring cell, the UE selects a cell that belongs to other cellsand that provides better signal characteristics than the cell of the BSthat is accessed by the UE. This process is called cell reselectiondifferently from the initial cell selection of the No. 2 process. Inthis case, temporal restriction conditions are placed in order for acell to be frequently reselected in response to a change of signalcharacteristic. A cell reselection procedure is described later indetail.

FIG. 5 is a flowchart illustrating a process of establishing RRCconnection.

UE sends an RRC connection request message that requests RRC connectionto a network (S510). The network sends an RRC connection establishmentmessage as a response to the RRC connection request (S520). Afterreceiving the RRC connection establishment message, the UE enters RRCconnected mode.

The UE sends an RRC connection establishment complete message used tocheck the successful completion of the RRC connection to the network(S530).

FIG. 6 is a flowchart illustrating an RRC connection reconfigurationprocess. An RRC connection reconfiguration is used to modify RRCconnection. This is used to establish/modify/release RBs, performhandover, and set up/modify/release measurements.

A network sends an RRC connection reconfiguration message for modifyingRRC connection to UE (S610). As a response to the RRC connectionreconfiguration message, the UE sends an RRC connection reconfigurationcomplete message used to check the successful completion of the RRCconnection reconfiguration to the network (S620).

A procedure of selecting, by UE, a cell is described in detail.

When UE is powered on or camps on in a cell, the UE selects/reselects acell having proper quality and performs procedures for being providedwith service.

UE in the RRC idle state needs to always select a cell having properquality and to be prepared to be provided with service through the cell.For example, UE that is initially powered on needs to select a cellhaving proper quality in order to register it with a network. If UE inthe RRC connection state enters the RRC idle state, the UE needs toselect a cell on which the UE will camp in the RRC idle state. Asdescribed above, a process of selecting, by UE, a cell that satisfiessome conditions in order to camp on in a service standby state, such asthe RRC idle state, is called cell selection. An important point is thatthe cell rapidly selects a cell because cell selection is performed inthe state in which the UE has not determined a cell on which the UE willcamp in the RRC idle state. Accordingly, if a cell is a cell thatprovides the quality of a radio signal of a specific reference orhigher, the cell may be selected in the cell selection process of UEalthough the cell is not a cell that provides the best radio signalquality to the UE.

A method and procedure in which UE selects a cell in 3GPP LTE isdescribed in detail with reference to 3GPP TS 36.304 V8.5.0 (2009-03)“User Equipment (UE) procedures in idle mode (Release 8).”

When UE is initially powered on, the UE searches for available PublicLand Mobile Networks (PLMNs) and selects a proper PLMN from which the UEis able to be provided with service. The PLMN is a network that isdeployed or operated by a mobile network operator. Each mobile networkoperator operates one or more PLMNs. Each PLMN may be identified byMobile Country Code (MCC) and Mobile Network Code (MNC). Informationabout the PLMN of a cell is included in system information andbroadcasted. The UE attempts to register it with the selected PLMN. Ifregistration is successful, the selected PLMN becomes a Registered PLMN(RPLMN). The network may signalize a PLMN list to the UE. In this case,PLMNs included in the PLMN list may be considered to be PLMNs, such asRPLMNs. The UE registered with the network needs to be able to be alwaysreachable by the network. If the UE is in the ECM-CONNECTED state(identically the RRC connection state), the network recognizes that theUE is being provided with service. If the UE is in the ECM-IDLE state(identically the RRC idle state), however, the situation of the UE isnot valid in an eNB, but is stored in the MME. In such a case, only theMME is informed of the location of the UE in the ECM-IDLE state throughthe granularity of the list of Tracking Areas (TAs). A single TA isidentified by a Tracking Area Identity (TAI) formed of the identifier ofa PLMN to which the TA belongs and Tracking Area Code (TAC) thatuniquely expresses the TA within the PLMN.

Thereafter, the UE selects a cell that belongs to cells provided by theselected PLMN and that has signal quality and characteristics on whichthe UE is able to be provided with proper service.

A cell selection process is basically divided into two types.

The first is an initial cell selection process. In this process, UE doesnot have preliminary information about a wireless channel. Accordingly,the UE searches for all wireless channels in order to find out a propercell. The UE searches for the strongest cell in each channel.Thereafter, if the UE has only to search for a suitable cell thatsatisfies a cell selection criterion, the UE selects the correspondingcell.

Next, the UE may select the cell using stored information or usinginformation broadcasted by the cell. Accordingly, cell selection may befast compared to an initial cell selection process. If the UE has onlyto search for a cell that satisfies the cell selection criterion, the UEselects the corresponding cell. If a suitable cell that satisfies thecell selection criterion is not retrieved though such a process, the UEperforms an initial cell selection process.

After the UE selects a specific cell through the cell selection process,the intensity or quality of a signal between the UE and a BS may bechanged due to a change in the mobility or wireless environment of theUE. Accordingly, if the quality of the selected cell is deteriorated,the UE may select another cell that provides better quality. If a cellis reselected as described above, the UE selects a cell that providesbetter signal quality than the currently selected cell. Such a processis called cell reselection. In general, a basic object of the cellreselection process is to select a cell that provides UE with the bestquality from a viewpoint of the quality of a radio signal.

In addition to the viewpoint of the quality of a radio signal, a networkmay determine priority corresponding to each frequency, and may informthe UE of the determined priorities. The UE that has received thepriorities preferentially takes into consideration the priorities in acell reselection process compared to a radio signal quality criterion.

As described above, there is a method of selecting or reselecting a cellaccording to the signal characteristics of a wireless environment. Inselecting a cell for reselection when a cell is reselected, thefollowing cell reselection methods may be present according to the RATand frequency characteristics of the cell.

-   -   Intra-frequency cell reselection: UE reselects a cell having the        same center frequency as that of RAT, such as a cell on which        the UE camps on.    -   Inter-frequency cell reselection: UE reselects a cell having a        different center frequency from that of RAT, such as a cell on        which the UE camps on    -   Inter-RAT cell reselection: UE reselects a cell that uses RAT        different from RAT on which the UE camps

The principle of a cell reselection process is as follows

First, UE measures the quality of a serving cell and neighbor cells forcell reselection.

Second, cell reselection is performed based on a cell reselectioncriterion. The cell reselection criterion has the followingcharacteristics in relation to the measurements of a serving cell andneighbor cells.

Intra-frequency cell reselection is basically based on ranking. Rankingis a task for defining a criterion value for evaluating cell reselectionand numbering cells using criterion values according to the size of thecriterion values. A cell having the best criterion is commonly calledthe best-ranked cell. The cell criterion value is based on the value ofa corresponding cell measured by UE, and may be a value to which afrequency offset or cell offset has been applied, if necessary.

Inter-frequency cell reselection is based on frequency priority providedby a network. UE attempts to camp on a frequency having the highestfrequency priority. A network may provide frequency priority that willbe applied by UEs within a cell in common through broadcastingsignaling, or may provide frequency-specific priority to each UE throughUE-dedicated signaling.

For the inter-frequency cell reselection, a network may provide UE witha parameter (e.g., a frequency-specific offset) used in cell reselectionfor each frequency.

For the intra-frequency cell reselection or the inter-frequency cellreselection, a network may provide UE with a Neighboring Cell List (NCL)used in cell reselection. The NCL includes a cell-specific parameter(e.g., a cell-specific offset) used in cell reselection.

For the intra-frequency or inter-frequency cell reselection, a networkmay provide UE with a cell reselection black list used in cellreselection. The UE does not perform cell reselection on a cell includedin the black list.

Ranking performed in a cell reselection evaluation process is describedbelow.

A ranking criterion used to apply priority to a cell is defined as inEquation 1.R _(s) =Q _(meas,s) +Q _(hyst) ,R _(n) =Q _(meas,s) −Q _(offset)

In this case, Rs is the ranking criterion of a serving cell, Rn is theranking criterion of a neighbor cell, Qmeas,s is the quality value ofthe serving cell measured by UE, Qmeas,n is the quality value of theneighbor cell measured by UE, Qhyst is the hysteresis value for ranking,and Qoffset is an offset between the two cells.

In Intra-frequency, if UE receives an offset “Qoffsets,n” between aserving cell and a neighbor cell, Qoffset=Qoffsets,n. If UE does notQoffsets,n, Qoffset=0.

In Inter-frequency, if UE receives an offset “Qoffsets,n” for acorresponding cell, Qoffset=Qoffsets,n+Qfrequency. If UE does notreceive “Qoffsets,n”, Qoffset=Qfrequency.

If the ranking criterion Rs of a serving cell and the ranking criterionRn of a neighbor cell are changed in a similar state, ranking priorityis frequency changed as a result of the change, and UE may alternatelyreselect the twos. Qhyst is a parameter that gives hysteresis to cellreselection so that UE is prevented from to alternately reselecting twocells.

UE measures RS of a serving cell and Rn of a neighbor cell according tothe above equation, considers a cell having the greatest rankingcriterion value to be the best-ranked cell, and reselects the cell.

In accordance with the criterion, it may be checked that the quality ofa cell is the most important criterion in cell reselection. If areselected cell is not a suitable cell, UE excludes a correspondingfrequency or a corresponding cell from the subject of cell reselection.

Radio Link Monitoring (RLM) is described below.

UE monitors downlink quality based on a cell-specific reference signalin order to detect the quality of the downlink radio link of a PCell.The UE estimates the quality of a downlink radio link in order tomonitor the quality of the downlink radio link of the PCell, andcompares the estimated quality with threshold values Qout and Qin. Thethreshold value Qout is defined as a level at which a downlink radiolink is unable to be stably received, which corresponds to a block errorrate of 10% of hypothetical PDCCH transmission by taking intoconsideration a PDFICH error. The threshold value Qin is defined as adownlink radio link quality level at which a downlink radio link is ableto be more stably received than compared to the level of Qout, whichcorresponds to a block error rate of 2% of hypothetical PDCCHtransmission by taking into consideration a PDFICH error.

A Radio Link Failure (RLF) is described below.

UE continues to perform measurements in order to maintain the quality ofa radio link with a serving cell from which the UE receives service. TheUE determines whether or not communication is impossible in a currentsituation due to the deterioration of the quality of the radio link withthe serving cell. If communication is almost impossible because thequality of the serving cell is too low, the UE determines the currentsituation to be an RLF.

If the RLF is determined, the UE abandons maintaining communication withthe current serving cell, selects a new cell through cell selection (orcell reselection) procedure, and attempts RRC connectionre-establishment with the new cell.

In the specification of 3GPP LTE, the following examples are taken ascases where normal communication is impossible.

-   -   A case where UE determines that there is a serious problem in        the quality of a downlink communication link (a case where the        quality of a PCell is determined to be low while performing RLM)        based on the radio quality measured results of the PHY layer of        the UE    -   A case where uplink transmission is problematic because a random        access procedure continues to fail in the MAC sublayer.    -   A case where uplink transmission is problematic because uplink        data transmission continues to fail in the RLC sublayer.    -   A case where handover is determined to have failed.    -   A case where a message received by UE does not pass through an        integrity check.

An RRC connection re-establishment procedure is described in more detailbelow.

FIG. 7 is a diagram illustrating an RRC connection re-establishmentprocedure.

Referring to FIG. 7, UE stops using all the radio bearers that have beenconfigured other than a Signaling Radio Bearer (SRB) #0, and initializesa variety of kinds of sublayers of an Access Stratum (AS) (S710).Furthermore, the UE configures each sublayer and the PHY layer as adefault configuration. In this process, the UE maintains the RRCconnection state.

The UE performs a cell selection procedure for performing an RRCconnection reconfiguration procedure (S720). The cell selectionprocedure of the RRC connection re-establishment procedure may beperformed in the same manner as the cell selection procedure that isperformed by the UE in the RRC idle state, although the UE maintains theRRC connection state.

After performing the cell selection procedure, the UE determines whetheror not a corresponding cell is a suitable cell by checking the systeminformation of the corresponding cell (S730). If the selected cell isdetermined to be a suitable E-UTRAN cell, the UE sends an RRC connectionre-establishment request message to the corresponding cell (S740).

Meanwhile, if the selected cell is determined to be a cell that uses RATdifferent from that of the E-UTRAN through the cell selection procedurefor performing the RRC connection re-establishment procedure, the UEstops the RRC connection re-establishment procedure and enters the RRCidle state (S750).

The UE may be implemented to finish checking whether the selected cellis a suitable cell through the cell selection procedure and thereception of the system information of the selected cell. To this end,the UE may drive a timer when the RRC connection re-establishmentprocedure is started. The timer may be stopped if it is determined thatthe UE has selected a suitable cell. If the timer expires, the UE mayconsider that the RRC connection re-establishment procedure has failed,and may enter the RRC idle state. Such a timer is hereinafter called anRLF timer. In LTE spec TS 36.331, a timer named “T311” may be used as anRLF timer. The UE may obtain the set value of the timer from the systeminformation of the serving cell.

If an RRC connection re-establishment request message is received fromthe UE and the request is accepted, a cell sends an RRC connectionre-establishment message to the UE.

The UE that has received the RRC connection re-establishment messagefrom the cell reconfigures a PDCP sublayer and an RLC sublayer with anSRB1. Furthermore, the UE calculates various key values related tosecurity setting, and reconfigures a PDCP sublayer responsible forsecurity as the newly calculated security key values. Accordingly, theSRB1 between the UE and the cell is open, and the UE and the cell mayexchange RRC control messages. The UE completes the restart of the SRB1,and sends an RRC connection re-establishment complete message indicativeof that the RRC connection re-establishment procedure has been completedto the cell (S760).

In contrast, if the RRC connection re-establishment request message isreceived from the UE and the request is not accepted, the cell sends anRRC connection re-establishment reject message to the UE.

If the RRC connection re-establishment procedure is successfullyperformed, the cell and the UE perform an RRC connection reconfigurationprocedure. Accordingly, the UE recovers the state prior to the executionof the RRC connection re-establishment procedure, and the continuity ofservice is guaranteed to the upmost.

A report on an RLF is described below.

When an RLF occurs or a handover failure occurs, UE reports such afailure event to a network in order to support the Mobility RobustnessOptimization (MRO) of the network.

After RRC connection re-establishment, the UE may provide the RLF reportto the eNB. Wireless measurement includes in the RLF report may be usedfor a potential reason of a failure in order to identify coverageproblems. Such information may be used to borrow such events as input toother algorithms by excluding the events in MRO evaluation for anintra-LTE mobility connection failure.

If RRC connection re-establishment fails or UE does not perform RRCconnection re-establishment, the UE may be connected again in idle mode,and may generate a valid RLF report on an eNB. For such an object, theUE may store information related to the most recent RLF or handoverfailure, and may inform an LTE cell that an RLF report is valid everyRRC connection (re)establishment and handover until the RLF report isfetched by a network or for 48 hours after an RLF or handover failure isdetected.

The UE maintains the information for a state shift and a change of RAT,and indicates that the RLF report is valid again after returning back toLTE RAT.

In an RRC connection establishment procedure, the validity of an RLFreport means that UE has experienced obstruction, such as a connectionfailure, and an RLF report attributable to the failure has not yet beentransferred to a network. The RLF report from the UE includes thefollowing information.

-   -   If the last cell (in the case of an RLF) that has provided        service to the UE or the E-CGI of a target for handover has not        been known, a PCI and frequency information are used instead.    -   The E-CGI of a cell at which re-establishment has been        attempted.    -   When initializing the last handover, for example, when a message        7 (an RRC connection reconfiguration) is received by the UE, the        E-CGI of a cell that has provided service to the UE.    -   The time that has elapsed from the initialization of the last        handover to a connection failure.    -   Information indicative of whether the connection failure is        attributable to an RLF or a handover failure.    -   Wireless measurements.    -   The location of a failure.

The eNB that has received the RLF from the UE may forward the report toan eNB that had provided service to the UE prior to the reportedconnection failure. Wireless measurements included in the RLF report maybe used to identify coverage issues as a potential cause of an RLF. Suchinformation may be used to send events to other algorithm as input againby excluding the events from the MRO evaluation of an intra-LTE mobilityconnection failure.

Measurement and a measurement report are described below.

In a mobile communication system, to support the mobility of UE isessential. Accordingly, the UE continues to measure the quality of aserving cell from which the UE is now provided with service and thequality of a neighbor cell. The UE reports measured results to a networkon a proper time, and the network provides optimum mobility to the UEthrough handover, etc. In general, measurement for this purpose iscalled a Radio Resource Management (RRM) measurement.

In order to provide information that may help an operator to operate anetwork in addition to the mobility support object, UE may performmeasurement for a specific object set by the network, and may reportmeasured results thereof to the network. For example, UE receives thebroadcast information of a specific cell that has been determined by thenetwork. The UE may report the cell identity (this is also called aglobal cell identity) of the specific cell, identity information aboutthe location to which the specific cell belongs (e.g., Tracking AreaCode) and/or other pieces of cell information (e.g., whether or not itis a member of a Closed Subscriber Group (CSG) cell) to the servingcell.

If UE checks that the quality of a specific area is very poor throughmeasurement while moving, the UE may report location information andmeasured results for cells having poor quality to a network. A networkmay perform network optimization based on the reports of the measuredresults of UEs that help the operation of the network.

In a mobile communication system in which frequency reuse (frequencyreuse factor) is 1, mobility is chiefly performed between differencecells that belong to the same frequency band. Accordingly, in order towell guarantee the mobility of UE, the UE needs to well measure thequality of neighboring cells having the same center frequency as aserving cell and information about the cells. As described above, themeasurement of a cell having the same center frequency as a serving cellis called intra-frequency measurement. UE performs intra-frequencymeasurement and reports measured results thereof to a network on aproper time so that the object of corresponding measured results isachieved.

A mobile communication operator may operate a network using a pluralityof frequency bands. If the service of a communication system is providedthrough a plurality of frequency bands, in order to guarantee optimummobility for UE, the UE needs to well measure the quality of neighboringcells having center frequencies from the center frequency of a servingcell and information about the cells. As described above, themeasurement of a cell having a center frequency different from thecenter frequency of a serving cell is called inter-frequencymeasurement. UE needs to be able to perform inter-frequency measurementand to report measured results thereof to a network on a proper time.

If UE supports the measurement of a heterogeneous network, the UE maymeasure the cell of a heterogeneous network according to a BSconfiguration. The measurement of such a heterogeneous network is calledinter-Radio Access Technology (RAT) measurement. For example, RAT mayinclude an UMTS Terrestrial Radio Access Network (UTRAN) and a GSM EDGERadio Access Network (GERAN) that comply with the 3GPP standard, and mayalso include CDMA 2000 systems that comply with the 3GPP2 standard.

FIG. 8 is a flowchart illustrating a method of performing measurement.

UE receives measurement configuration information from a BS (S810). Amessage including the measurement configuration information is called ameasurement configuration message. The UE performs measurements based onthe measurement configuration information (S820). If measured resultssatisfy report conditions within the measurement configurationinformation, the UE reports the measured results to the BS (S830). Amessage including the measured results is called a measurement reportmessage.

The measurement configuration information may include the followinginformation.

(1) Measurement object information: it is information about the objecton which UE will perform measurement. A measurement object includes atleast one of an intra-frequency measurement object that is the object ofmeasurement within a cell, an inter-frequency measurement object that isthe object of measurement between cells, and an inter-RAT measurementobject that is the object of inter-RAT measurement. For example, theintra-frequency measurement object may indicate a neighboring cellhaving the same frequency band as a serving cell, the inter-frequencymeasurement object may indicate a neighboring cell having a frequencyband different form that of a serving cell, and the inter-RATmeasurement object may indicate a neighboring cell having RAT differentfrom that of a serving cell.

(2) Reporting configuration information: this is information aboutreport conditions regarding when UE reports measured results and areport type. The report conditions may include information about anevent or cycle on which the report of the measured results is triggered.The report type is information regarding that the measured results willbe configured in what type.

(3) Measurement identity information: this is information about ameasurement identity that associates a measurement object with areporting configuration so that UE determines to report what measurementobject when and in what type. Each measurement identity associates asingle measurement object with a single reporting configuration. Byconfiguring a plurality of measurement identities, one or more reportingconfigurations may be associated with the same measurement object, andone or more measurement objects may also be associated with the samereporting configuration. A measurement identity may be used as areference numeral within a measurement report. Measurement identityinformation may be included in a measurement report message, and may beindicative that measured results are for which measurement object andthat a measurement report has occurred due to what report conditions.

(4) Quantity configuration information: quality configurationinformation defines the amount of measurement and defines associatedfiltering used for reports related to the evaluation of all events andmeasurement types thereof. A single filter may be set in eachmeasurement quantity.

(5) Measurement gap information: this is information about a measurementgap, that is, a section that may be used for UE to perform onlymeasurement by not taking into consideration data transmission with aserving cell because downlink transmission or uplink transmission hasnot been scheduled.

In order to perform a measurement procedure, UE has a measurement objectlist, a measurement report configuration list, and a measurementidentity list.

In 3GPP LTE, a BS may configure only one measurement object for a singlefrequency band in relation to UE. In accordance with Paragraph 5.5.43GPP TS 36.331 V8.5.0 (2009-03) “Evolved Universal Terrestrial RadioAccess (E-UTRA) Radio Resource Control (RRC); Protocol specification(Release 8),” events that trigger measurement reports are defined in thefollowing table.

TABLE 1 Event Report Conditions Event A1 Serving becomes better thanthreshold Event A2 Serving becomes worse than threshold Event A3Neighbour becomes offset better than serving Event A4 Neighbour becomesbetter than threshold Event A5 Serving becomes worse than threshold1 andneighbour becomes better than threshold2 Event B1 Inter RAT neighbourbecomes better than threshold Event B2 Serving becomes worse thanthreshold1 and inter RAT neighbour becomes better than threshold2

If the measured results of UE satisfy a set event, the UE sends ameasurement report message to a BS.

FIG. 9 illustrates an example of a measurement configuration configuredto UE.

First, a measurement identity 1 901 connects an intra-frequencymeasurement object and a reporting configuration 1. UE performsintra-cell measurement (intra-frequency measurement), and the reportingconfiguration 1 is used to determine the criterion of a measurementresult report and a report type.

A measurement identity 2 902 is connected to the intra-frequencymeasurement object like the measurement identity 1 901, but it connectsthe intra-frequency measurement object to a reporting configuration 2.UE performs measurement, and the reporting configuration 2 is used todetermine the criterion of a measurement result report and a reporttype.

In accordance with the measurement identity 1 901 and the measurementidentity 2 902, UE sends the measured results of the intra-frequencymeasurement object although the measured results satisfy any one of thereporting configuration 1 and the reporting configuration 2.

A measurement identity 3 903 connects an inter-frequency measurementobject 1 and a reporting configuration 3. UE reports the measuredresults of the inter-frequency measurement object 1 if the measuredresults satisfy report conditions included in the reportingconfiguration 1.

A measurement identity 4 904 connects an inter-frequency measurementobject 2 and the reporting configuration 2. UE reports the measuredresults of the inter-frequency measurement object 2 if the measuredresults satisfy report conditions included in the reportingconfiguration 2.

Meanwhile, a measurement object, a reporting configuration and/or ameasurement identity may be added, changed and/or deleted. This may beindicated in such a manner that a BS sends a new measurementconfiguration message to UE or sends a measurement configuration changemessage to the UE.

FIG. 10 illustrates an example in which a measurement identity isdeleted. When a measurement identity 2 902 is deleted, the measurementof a measurement object associated with the measurement identity 2 902is stopped, and a measurement report is not transmitted. A measurementobject or a reporting configuration associated with a measurementidentity may not be changed.

FIG. 11 illustrates an example in which a measurement object is deleted.When an inter-frequency measurement object 1 is deleted, UE also deletesan associated measurement identity 3 903. The measurement of theinter-frequency measurement object 1 is stopped, and a measurementreport is not transmitted. However, a reporting configuration associatedwith the deleted inter-frequency measurement object 1 may not be changedor deleted.

When a reporting configuration is removed, UE also removes an associatedmeasurement identity. The UE stops the measurement of a measurementobject associated by the associated measurement identity. However, ameasurement object associated with a deleted reporting configuration maynot be changed or deleted.

A measurement report may include a measurement identity, the measuredquality of a serving cell, and the measured results of a neighboringcell. A measurement identity identifies a measurement object whosemeasurement report has been triggered. The measured results of aneighboring cell may include the cell identity and measured quality ofthe neighboring cell. Measured quality may include at least one ofReference Signal Received Power (RSRP) and Reference Signal ReceivedQuality (RSRQ).

Accessibility measurement is described below.

To handle the non-availability measurement of connection for UE has manyaspects. In this case, both common channels and connection proceduresare handled. In order to inform a network of the non-availability ofconnection and thus assist parameter optimization for increasing theavailability of connection, UE performs accessibility measurement whenconnection establishment fails. For the accessibility measurement, theUE performs the following logging.

-   -   A time stamp derived using a relative timer for counting the        time between a failure and a report is included. A storage time        for accessibility measurement is 48 hours.    -   Reporting the number of transmitted random access preamble is        supported.    -   Indicating whether or not a maximum power level has been reached        is supported.    -   Indicating whether or not a contention has been detected during        a random access procedure for connection establishment is        included.

A Tacking Collection Entity (TCE) is described below.

A subscriber and equipment traces very detailed information to one ormore specific mobiles in terms of a call level. The data may be anadditional source for information for performance measurements.Furthermore, the data enables a further deep monitoring and optimizationoperation to be performed. Unlike in a performance measurement that isalways the source of information, the trace may be activated in responseto user needs/requirements during a limited time interval for a specificanalysis purpose. The trace plays a very important role in operations,such as determining a fundamental cause of a malfunctioning mobile, animproved troubleshoot, the optimization the use of resource and quality,control of Radio Frequency (RF) coverage, capacity improvements, ananalysis of a break-up phenomenon during a call, and the check of anUMTS procedure between the ends of a core network and an UTRAN.

For service initiated by a specific user (e.g., an International MobileSubscriber Identity (IMSI)), a mobile type (e.g., an InternationalMobile Equipment Identity (IMEI) Software Version (IMEISV)), or a user,a function for logging data on an interface in a call level enablesinformation that may not be inferred from performance measurements, suchthe recognition of the final user QoS during a call (e.g., requested QoSversus provided QoS), a correlation between protocol messages and RFmeasurements, or mutual information processing operation with specificmobile vendors, to be obtained. Trace data is collected by the TCE.

A Minimization of Driving Tests (MDT) is described below.

An MDT enables UE to perform measurements and to report the results ofthe measurement instead of a drive test in which conventional operatorsmeasure the quality of cells using vehicles for the coverageoptimization of the cells. Coverage varies depending on the location ofa BS, the deployment of surrounding buildings, and an environment usedby a user. Accordingly, an operator needs to periodically perform adrive test, which requires great expense and lots of resources. In orderto overcome such a disadvantage, there is proposed an MDT in which anoperator measures coverage using UE.

An operator may synthesize MDT measurement values received from multipleUEs, may write a coverage map indicative whether service is available inan overall area in which an operator provides the service and adistribution of qualities of service, and may use the coverage map innetwork operations and optimization. For example, when a coverageproblem in a specific area is reported by UE, an operator may extend thecoverage of a cell in the corresponding area by increasing thetransmission power of a BS that provides service in the correspondingarea. The time and expense for network optimization can be minimizedthrough such as method.

The MDT has been made based on the framework of a trace function, thatis, one of the tools of an operator for Operation, Administration, andMaintenance (OAM). The trace function provides an operator with theability to perform trace and log the behaviors of UE, and thus it mayenable a main cause of a defective function on the UE side to bedetermined. Traced data is collected over a network, and is called aTrace Collection Entity (TCE). An operator uses data collected by a TCEfor analysis and evaluation purposes. A trace function used for an MDTincludes signaling based on the trace function and management based ontrace functions. Signaling based on a trace function is used to activatean MDT task toward specific UE, whereas management based on tracefunctions is used to activate an MDT task without being limited tospecific UE.

An MDT may be divided into two types: a logged MDT and an immediate MDTdepending on whether UE reports measured and stored log data in areal-time manner or in real time. The logged MDT is a method by which UEperforms MDT measurements, logs measurement data, and subsequently sendsthe logged data to a network. In contrast, the immediate MDT is a methodby which UE performs MDT measurements and immediately sends measurementdata to a network. In accordance with the logged MDT, UE may perform MDTmeasurements in the RRC idle state. In accordance with the immediateMDT, UE performs MDT measurements in the RRC connection state.

FIG. 12 is a flowchart illustrating a method of performing a logged MDT.

Referring to FIG. 12, UE receives a logged measurement configuration(S1210). The logged measurement configuration may be included in an RRCmessage, and may be transmitted through a downlink control channel. Thelogged measurement configuration may include at least one of the ID of aTCE, information about the time that is a reference on which logging isperformed (i.e., a reference time), logging duration, a logginginterval, and information about an area configuration. The logginginterval is indicative of an interval in which measured results arestored. The logging duration is indicative of duration for which UEperforms a logged MDT. The reference time is indicative of the time thatis the reference of duration for which a logged MDT is performed. Thearea configuration is indicative of an area on which the execution oflogging has been requested by UE.

Meanwhile, the UE starts a validity timer when receiving the loggedmeasurement configuration. The validity timer is indicative of thelifespan of the logged measurement configuration, and may be specifiedbased on information about logging duration. The duration of thevalidity timer may be indicative of the validity of measured resultsowned by the UE in addition to the valid lifespan of the loggedmeasurement configuration.

As described above, a procedure in which the UE performs the loggedmeasurement configuration and a corresponding overall procedure isperformed is called a configuration phase.

When the UE enters the RRC idle state (S1221), the UE logs measuredresults while the validity timer operates (S1222). The value of themeasured results may be RSRP, RSRQ, Received Signal Code Power (RSCP),or Ec/No. Information on which the measured results have been logged ishereinafter called logged measurement and/or a measurement result log. Atemporal section in which UE logs measured results at least more thanonce is called a logging phase.

To perform the logged MDT based on the logged measurement configurationby the UE may vary depending on the location where the UE is present.

FIG. 13 is a diagram illustrating an example of a logged MDT accordingto a logged area.

A network may configure a logging area, that is, an area on which UE hasto log. The logging area may be expressed as a cell list, or may beexpressed as a tracking area/location area list. If a logging area isconfigured or UE, the UE stops logging if it deviates from the loggingarea.

Referring to FIG. 13, a first area 1310 and a third area 1330 are areasconfigured as logging areas, and a second area 1320 is an area in whichlogging is not permitted. UE performs logging in the first area 1310,but does not perform logging in the second area 1320. The UE performlogging again when it moves from the second area 1320 to the third area1330.

FIG. 14 is a diagram illustrating an example of a logged MDT accordingto a change of RAT.

UE performs logging only when it camps on RAT from which a loggedmeasurement configuration has been received, but stops logging in otherRATs. In this case, the UE may log cell information for other RATs inaddition to the RAT on which the UE camps.

A first area 1410 and a third area 1430 are E-UTRAN areas, and a secondarea 1420 is an UTRAN area. A logged measurement configuration isreceived from the E-UTRAN. UE does not perform MDT measurement when itenters the second area 1420.

Referring back to FIG. 12, the UE enters the RRC connection state(S1231). If logged measurement to be reported is present, the UE informsan eNB that the logged measurement to be reported is present (S1232).The UE may inform the eNB that the logged measurement to be reported ispresent when RRC connection is established, RRC connection isre-established, or RRC connection is reconfigured. Furthermore, if theUE performs handover, the UE may inform the eNB that logged measurementfor a handover target cell is present. To inform, by the UE, the eNBthat the logged measurement is present may include including a loggedmeasurement-available indicator, that is, indication information thatprovides notification of the presence of the logged measurement, in anRRC message transmitted from the UE to the eNB, and sending the RRCmessage including the logged measurement-available indicator. The RRCmessage may be an RRC connection establishment complete message, an RRCconnection re-establishment complete message, an RRC reconfigurationcomplete message, or a handover complete message.

When a signal that provides notification of the presence of the loggedmeasurement is received from the UE, the eNB requests the UE to reportthe logged measurement (S1233). To request the logged measurement to bereported may include including a logged measurement report requestparameter regarding information indicative of the request in an RRCmessage, and sending the RRC message including the logged measurementreport request parameter. The RRC message may be a UE informationrequest message.

When the UE receives the request to report the logged measurement fromthe eNB, the UE reports the logged measurement to the eNB (S1234). Toreport the logged measurement to the eNB may include including a loggedmeasurement report, including the logged measurement, in an RRC message,and sending the RRC message to the eNB. The RRC message may be a UEinformation report message. In reporting the logged measurement, the UEmay report all the logged measurements of the UE at a report time pointto the eNB, or may report some of all the logged measurements to theeNB. If some of the logged measurements are reported, the reported somemeasurements may be discarded.

A phase in which a process of informing, by the UE, the eNB that thelogged measurement is present, receiving the request to report thelogged measurement from the eNB, and reporting the logged measurement inresponse to the request is performed as described above is called areporting phase.

While the logged MDT is performed, the UE chiefly measures a wirelessenvironment. The MDT measurement may include the identity of a cell andthe signal quality and/or signal intensity of the cell. The MDTmeasurement may include a measurement time and a measurement place. Thefollowing table illustrates contents logged by UE.

TABLE 2 Parameter (set) Description Serving cell identity Global cellidentity of serving cell Measured results of Measured RSRP of servingcell serving cell Measured RSRQ of serving cell Measured results of Cellidentities of measured E-UTRA cells, neighbor cell measured results ofE-UTRA cells Cell identities of measured UTRA cells, measured results ofUTRA cells Cell identities of measured GERAN cells, measured results ofGERAN cells Cell identities of measured CDMA 2000 cells, measuredresults of CDMA 2000 cells Time stamp The moment of logging measurementresults, calculated (as current time minus absolute TimeStamp inseconds) Location information Detailed location information at themoment of logging

Pieces of information logged at different logging time points may bestored as follows so that they are classified as different log entries.

FIG. 15 is a diagram illustrating an example of logged measurements.

Logged measurement includes one or more log entries.

The log entry includes a logging location, a logging time, a servingcell identity, the measured results of a serving cell, and the measuredresults of a neighboring cell.

The logging location is indicative of the location where UE wasmeasured. The logging time is indicative of the time when UE wasmeasured. Pieces of information logged at different logging times arestored in different log entries.

The serving cell identity may include a cell identity in Layer 3, whichis called a Global Cell Identity (GCI). The GCI is a set of a PhysicalCell Identity (PCI) and a PLMN identity.

Meanwhile, UE may analyze indices related to the performance of the UEin addition to a wireless environment, and log the analyzed indices. Forexample, the indices may include throughput, an erroneoustransmission/reception rate, etc.

Referring back to FIG. 12, the logging phase and the reporting phase maybe present in logging duration plural times (S1241, S1242).

When logged measurement is reported, the eNB may record/store the loggedmeasurement in the TCE.

After the validity timer expires, that is, after the logging durationelapses, if the UE has logged measurement that has not yet beenreported, the UE performs a procedure for reporting the loggedmeasurement to the eNB. A phase in which an overall procedure forreporting the logged measurement is called a post-reporting phase.

After the logging duration is terminated, the UE discards the loggedmeasurement configuration and starts a conservation timer. After thelogging duration is terminated, the UE stops MDT measurement. However,already logged measurement remains without being discarded. Theconservation timer is indicative of the lifespan of the remaining loggedmeasurement.

When the UE enters the RRC connection state before the conservationtimer expires (S1251), the UE may report not-reported logged measurementto the eNB. In such a case, the aforementioned procedure for a loggedmeasurement report may be performed (S1252, S1253, and S1254). If theconservation timer expires, the remaining logged measurement may bediscarded. When logged measurement is reported, the eNB may record/storethe logged measurement in the TCE.

The conservation timer may be fixed to a value predetermined in the UE,and may be previously set in the UE. For example, the value of theconservation timer may be 48 hours. Alternatively, the value of theconservation timer may be included in a logged measurement configurationand transferred to the UE, or may be included in another RRC message andtransferred to the UE.

Meanwhile, when a new logged measurement configuration is transferred tothe UE, the UE may update an existing logged measurement configurationwith a newly obtained logged measurement configuration. In such a case,the validity timer may be started again from a time point at which alogged measurement configuration is newly received. Furthermore, loggedmeasurement based on a previous logged measurement configuration may bediscarded.

FIG. 16 is a diagram illustrating an example of an immediate MDT. Theimmediate MDT is based on a Radio Resource Management (RRM) measurementand report mechanism. When a measurement report is made, informationrelated to the location is additionally added to the immediate MDT andreported to an eNB.

Referring to FIG. 16, UE receives an RRC connection reconfigurationmessage (S1610), and sends an RRC connection reconfiguration completemessage (S1620). Accordingly, the UE enters the RRC connection state.The UE may receive a measurement configuration by receiving the RRCconnection reconfiguration message. In the example of FIG. 16, themeasurement configuration is received through the RRC connectionreconfiguration message, but may be included in another RRC message andtransmitted.

The UE performs measurement and evaluation in the RRC connection state(S1631), and reports measured results to an eNB (S1632). In theimmediate MDT, the measured results may provide precise locationinformation as in the example of Global Navigation Satellite System(GNSS) location information if possible. For location measurement, suchas fingerprint, the measured results may provide neighbor cellmeasurement information that may be used to determine the location ofthe UE.

From FIG. 16, it may be seen that even after the measurement andevaluation (S1631) and report (S1632) that are first performed, the UEreports the measured results to the eNB (S1643) right after performingmeasurement and evaluation (S1642). This is the greatest differencebetween the logged MDT and the immediate MDT.

The aforementioned RLF report and accessibility measurement may beconsidered to be part of the MDT. Positioning is described below.

A positioning function provides means for determining the geographicallocation and/or speed of UE based on the measurement of a radio signal.Location information may be requested by a client (e.g., an application)with which UE is combined or a client that is present in a core networkor attached to the core network, and may be reported to the client. Thelocation information is reported according to a standard format, and maybe implemented based on a cell or as geographical coordinates along withthe estimated error (uncertainty) of the location and speed of the UEand, if possible, a location method (or a list of methods) used toobtain location estimation.

Most of activated or deactivated UEs within a network may use a LoCationService (LCS) characteristic without compromising the wirelesstransmission or signaling capabilities of an E-UTRAN.

The uncertainty of location information depends on a method used, thelocation of UE within a coverage area, and a movement of the UE. Variousdesign options (e.g., the size of a cell, an adjustable antennatechnology, path loss estimates, timing accuracy, and eNB surveys) of anE-UTRAN system enable a network operator to provide a UE positioningmethod that is suitable for the market and that is cost-effective.

Various use examples for positioning information are present.Positioning functions may be used by an EPS internally, value-addednetwork services, UE itself, or third-party service over a network. Thefunctions may also be used by essential or additional emergenceservices. Location service may not be exclusively assigned for thelocation service.

Positioning methods supported in an E-UTRAN may include anetwork-supported GNSS method, a downlink positioning method, anenhanced cell identity (ID) (E-CID) method, and an uplink positioningmethod. A hybrid positioning method to which one or more of theaforementioned methods are applied at the same time is also possible.

The network-supported GNSS method is based on UE equipped with awireless receiver capable of receiving GNSS signals. The GNSS includes aGlobal Positioning System (GPS), Galileo, a global navigation satellitesystem (GLONASS), Space Based Augmentation Systems (SBAS), and a QuasiZenith Satellite System (QZSS). In accordance with the network-supportedGNSS method, different GNSSs may be individually used to determine thelocation of UE, or at least one system may be combined and used.

The downlink positioning method also called Observed Time Difference ofArrival (OTDOA) is based on the measured timing of downlink signalstransmitted from a plurality of eNBs to UE. The UE measures the timingof the received signals using assistance data received from apositioning server. The measured results are used to determine thelocation of the UE in relation to neighboring eNBs.

In the cell identity (CID) positioning method, the location of UE isestimated based on the knowledgement of the serving eNB and serving cellof the UE. Information about the serving eNB and the serving cell may beobtained by paging, the update of a tracking area, or other methods. TheE-CID positioning method means a technology that uses measurementsdifferent from those of additional UE and/or E-UTRAN radio resources inorder to improve UE location estimation.

Although the E-CID positioning method uses some identical measurement asin a measurement control system on the RRC protocol, UE is not expectedto perform additional measurement for only positioning. For example, aseparate measurement configuration or measurement control message is notprovided for positioning, and the UE is not requested to take anadditional measurement action, but reports its own valid measurement.

The uplink positioning method also called Uplink Time Difference OFArrival (UTDOA) is based on measurement timing in a plurality ofLocation Measurement Units (LMUs) for an uplink signal transmitted byUE. The LMU measures signal reception timing using assistance datareceived from a positioning server, the measured results are used toestimate the location of the UE.

FIG. 17 is a diagram illustrating an example of the structure of awireless communication system to which the positioning of UE is appliedaccording to an embodiment of the present invention.

An MME may receive a request for location service related to a specifictarget UE from a specific entity (e.g., a Global Mobile Location Center(GMLC) or UE). Furthermore, for purposes, such as an IP MultimediaSubsystem (IMS) emergency call from a UE, the MME may determine toinitiate location service for a specific target UE. Accordingly, the MMEsends a location service request to an Evolved-Service Mobile LocationCenter (E-SMLC).

The E-SMLC processes the location service request. The E-SMLC maytransfer assistance data to the target UE in order to help UE-basedand/or UE support positioning. The E-SMLC may perform the positioning ofthe target UE. In processing location service according to an uplinkmethod, the E-SMLC may transfer configuration data to selected LocationMeasurement Units (LMUs). Accordingly, the E-SMLC may return the resultsof the location service to the MME. Meanwhile, if the location serviceis requested by another entity (the UE or the E-SMLC) not the MME, theMME may return the results to a corresponding entity.

A SUPL Location Platform (SLP) is a Secure User Plane Location (SUPL)entity responsible for positioning on the user plane.

Location-related functions are provided in order to support thepositioning of a target UE and the transfer of location assistance datato the UE. Such functions may be properly distributed within astructure, such as that of FIG. 17, and may be implemented. Meanwhile,reference to FIG. 18 may be made for operations related to locationservice that may be performed between such entities.

FIG. 18 is a diagram illustrating overall procedures for locationservice according to an embodiment of the present invention.

If an MME receives a location service request when UE is in the ECM-IDLEstate, the MME establishes signaling connection with the UE, andperforms a network triggering service request in order to assign aspecific eNB. It is assumed that the UE enters a connection state beforethe overall procedures illustrated in FIG. 18 are started.

Location service is started in response to a location service requestfrom a specific entity (S1810). The location service request may bestarted as follows.

The UE may request location service (e.g., positioning or the transferof assistance data) from a serving MME on an NAS level (S1810 a). Aspecific entity within an Evolved Packet Core (EPC), such as a GMLC, mayrequest location service (e.g., positioning) for the target UE from theserving MME (S1810 b). The serving MME for the target UE may determinewhether or not the location service is necessary, and may autonomouslyrequest the location service if the location service is necessary (S1810c). This may be for placing the UE at a specific location or for anemergency call.

The MME transfers the location service request to an E-SMLC (S1820).

The E-SMLC performs a location service procedure in response to thelocation service request (S1830). The E-SMLC may perform the locationservice procedure along with the serving eNB of the UE (S1830 a). Thismay include obtaining positioning measurement or assistance data. Fordownlink positioning, the E-SMLC may perform the location serviceprocedure along with the UE (S1830 b) along with S1830 a or instead ofS1830 a. This may include obtaining location estimation or positioningmeasurement or transferring location assistance data to the UE. Foruplink positioning (e.g., UTDOA), the E-SMLC may perform the locationservice procedure along with one or more LMUs for the target UE (S1830c) along with S1830 a. This may include obtaining positioningmeasurement.

The E-SMLC provides the MME with a location service response (S1840).The location service response may include required results. For example,an indicator indicative of a success or failure and/or locationestimation for the UE may be included.

The location service response is provided to the entity that hasrequested the location service (S1850). If the location service requestis started by the UE as in S1810 a, the MME may transfer the locationservice response to the UE (S1850 a). In such a case, the locationservice response may include results that have been requested or arerequired like the location estimation of the UE. If the location servicerequest is started by a specific entity within the EPC as in S1810 b,the MME may transfer the location service response to the correspondingentity (S1850 b). In such a case, the location service response mayinclude results that have been requested or are required like thelocation estimation of the UE. If the location service request isautonomously started by the MME as in S1810 c, the location serviceresponse received from the E-SMLC may be used for the location service(S1850 c).

A positioning operation in a wireless communication system is describedbelow.

Unlike in location service support for specific UEs, an E-SMLC mayinteract with elements within an E-UTRAN in order to obtain measurementinformation which supports one or more positioning methods for all UEs.

Support of a downlink positioning method: an E-SMLC may obtainlocation-related information in order to support a downlink positioningmethod. To this end, the E-SMLC may interact with an eNB accessible tothe MME that has been signaling-connected to the E-SMLC. Thelocation-related information may include an absolute GNSS time or timinginformation about the eNB related to the timing of other eNBs.Furthermore, the information may include information about supportedcells, and may include a Positioning Reference Signal (PRS) schedule,for example. Signaling access between the E-SMLC and the eNB may beperformed through the MME that maintains signaling access to the E-SMLCand the eNB.

Support of an uplink location method: the E-SMLC may interact with theserving eNB of a target UE in order to recover configuration informationabout the target UE for supporting an uplink positioning method. Theconfiguration information may include information requested by an LMU inorder to support uplink time measurement. The E-SMLC may inform theserving eNB that it is necessary to send an SRS signal to the UE foruplink positioning. If requested resources are not available, the eNBmay assign other resources and reports the assigned resources to theE-SMLC. Furthermore, the E-SMLC may request the LMU to perform uplinktime measurement and to report measured results thereof.

The operations of entities related to UE positioning in a wirelesscommunication system are described in detail below.

The UE may send a signal necessary for uplink-based UE locationmeasurement. Furthermore, the UE may measure downlink signals from otherresources, such as an E-UTRAN and other GNSS systems. A measurementmethod may be determined based on a selected positioning method.

The UE may include a location service application, or may access alocation service application through communication with a network oranother application included in the UE. The location service applicationincludes a measurement and calculation function that is required todetermine the location of the UE along with the support of a requirednetwork or without the support of a network.

For example, the UE may include an independent positioning function(e.g., GPSs), and may report results thereof independently from thetransmission of an E-UTRAN. The UE equipped with the independentpositioning function may use support information obtained by a network.

The eNB is an element of an E-UTRAN that provides measured results forlocation estimation, and may measure a radio signal for target UE andsend the measurement to an E-SMLC. The eNB may perform measurement inresponse to a request, or may perform measurement and a report regularlyor when a specific wireless state is changed. The eNB may configure theUE so that the UE sends a periodic SRS.

The E-SMLC manages the support of location service for target UE, andthe management includes the positioning of the UE and the transfer ofassistance data to the UE. The E-SMLC may interact with the serving eNBof the UE in order to obtain location measurement for the UE. Themeasurement includes uplink measurement by an eNB and downlinkmeasurement by UE. From among them, the downlink measurement by the UEmay be provided to an eNB through another function, such as the supportof handover. In order to enable an uplink positioning method and for anLMU to obtain target UE configuration data required to compute thetiming of a signal, the E-SMLC may interface with an eNB in order toinstruct the serving eNB that the UE is required to send an SRS signal.The E-SMLC may select a set of LMUs used for UTDOA positioning. TheE-SMLC may interact with selected LMUs in order to request timingmeasurement. If there is a request, the E-SMLC may interact with thetarget UE in order to transfer assistance data or obtain locationestimation.

For the positioning of the target UE, the E-SMLC may determine apositioning method that will be used based on factors, including an LCSclient type, required QoS, UE positioning capabilities, and thepositioning capabilities of an eNB. Accordingly, the E-SMLC may applythe positioning method to the UE and/or the serving eNB. The positioningmethod includes location estimation for a UE-based positioning methodand/or location measurement for a UE support and network-basedpositioning method. The E-SMLC may combine all received results, and maydetermine single location estimation for target UE. Supplementaryinformation, such as the accuracy and speed of location estimation mayalso be determined.

An LMU performs measurement and transfers measured results to an E-SMLC.All types of location measurement obtained by the LMU may be provided tothe E-SMLC. A UE positioning request may be accompanied by measurementperformed by a plurality of LMUs.

If UE reports information about the location of unrestricted coveragealthough location information desired to be collected by a network isrestricted to a specific time zone or a specific network area, thenetwork receives excessively obtained location information, therebyincreasing overhead. Furthermore, there may be a problem in that poweris unnecessarily consumed because UE performs positioning in order toobtain location information having a low importance. In a currentwireless communication system, however, there is no method ofrestricting the positioning of UE to the time or a network area intendedby a network.

The present invention proposes a report method based on a scheme forrestricting the positioning of UE so that information about a restrictedlocation desired to be collected by a network can be collected.

FIG. 19 is a diagram illustrating a report method based on positioningrestriction according to an embodiment of the present invention.

Referring to FIG. 19, UE receives positioning restriction informationfrom a network (S1910), determines whether or not to perform positioningat a specific time interval and/or in a specific area based on thepositioning restriction information (S1920), obtains information aboutthe location of the corresponding coverage if the positioning ispermitted (S1930), and reports the obtained location information to thenetwork (S1940).

The positioning restriction information may be explicitly configured forthe UE independently of other pieces of configuration information. Thatis, the positioning restriction information may be signaled to the UE asinformation independent from other pieces of configuration information.The positioning restriction information may be signaled to the UE alongwith information related to the measurement of a measurementconfiguration. The positioning restriction information may be signaledto the UE along with information related to the logged MDT of a loggedmeasurement configuration.

The positioning restriction information may be implicitly configuredwhen other pieces of configuration information are configured for theUE. For example, if information that restricts the logging area of alogged MDT is configured for UE along with a logged measurementconfiguration, the UE may consider the logging area restrictioninformation of the logged MDT to be area information for positioningrestriction. Furthermore, logging duration of an logged MDT included ina logged measurement configuration may be considered to be timeinformation for positioning restriction.

The validity of positioning restriction information may depend oninformation about the configuration of a configuration message that istransmitted along with positioning information. For example, in a loggedMDT, if positioning restriction information is included in a loggedmeasurement configuration and transmitted, the validity of thepositioning information may depend on the validity timer of the loggedmeasurement configuration. Furthermore, if positioning information isincluded in a measurement configuration and transmitted, the validity ofthe positioning information may depend on the validity of themeasurement configuration. In the case of an immediate MDT, if UE hasmoved to a cell through cell reselection and/or handover, positioningrestriction information may be no longer valid because measurementconfiguration is no longer valid. In this case, if the positioningrestriction information is transmitted or has been transmitted through amessage that is independently signaled or if information related to thevalidity of the positioning restriction information is transmitted alongwith the message, the validity of the positioning restrictioninformation may be implemented to be valid for a time interval indicatedby validity-related information and/or for a specific time intervalpreviously set by UE.

Positioning restriction may be positioning information that restricts UEso that the UE performs positioning for a specific time interval only.If the positioning is restricted to the specific time interval,positioning restriction information may be implemented to be indicativeof the specific time interval.

-   -   The time information may include only the specific time        interval. In such a case, when the time information is received,        the UE starts a restriction timer set to the specific time        interval. The UE obtains location information by performing        positioning while the restriction timer is being driven.    -   The time information may include a start time point and an end        time point. In such a case, UE may start positioning at the        start time, and may continue performing the positioning until        the end time.

Positioning restriction may be positioning information that restricts UEso that the UE performs positioning only in a specific network area. Ifthe positioning is restricted to the specific network area, positioningrestriction information may be implemented to be indicative of thespecific network area.

-   -   Specific network area information may be a cell identity list.        In such a case, UE may obtain location information by performing        positioning only if a serving cell is now included in the cell        identity list.    -   Specific network area information may be a frequency list. In        such a case, UE may obtain location information by performing        positioning only if a serving cell is now included in the        frequency list.    -   Specific network area information may be a Tracking Area Code        (TAC) or Tracking Area Identity (TAI) list. In this case, the        TAI is an identifier that includes a Mobile Country Code (MCC),        a Mobile Network Code (MNC), and a TAC. In such a case, UE may        obtain location information by performing positioning only if a        tracking area to which a serving cell now belongs is included in        the received TAC/TAI list.    -   Specific network area information may be a PLMN ID list. In such        a case, UE may obtain location information by performing        positioning only if a PLMN to which a serving cell now belongs        is included in the PLMN ID list.    -   Specific network area information may be a specific RAT        indicator. In such a case, UE may obtain location information by        performing positioning only if a serving RAT is now a specific        RAT.    -   Meanwhile, specific network area information may be a        combination of pieces of network region information, such as        that described above.

In the case where a network has sent positioning restriction informationthat restricts positioning, performed by UE in the RRC connection state,to the UE, if the UE performs handover to another cell, a source cellmay forward the positioning restriction information to a target cell.The target cell may reconfigure positioning restriction informationsuitable for the UE based on the received positioning restrictioninformation, and may provide the reconfigured positioning restrictioninformation to the UE. In such a case, the reconfigured positioningrestriction information may be provided to the UE through a handovercommand or through signaling after the handover is completed. If thepositioning restriction information transmitted from the source cell tothe target cell is positioning restriction according to a time interval,the source cell may provide the UE with information indicative of theremaining time for the positioning.

FIG. 20 is a flowchart illustrating an example of a report method basedon restricted positioning according to an embodiment of the presentinvention. The example of FIG. 20 illustrates a case where a timeinterval in which positioning is performed is restricted in the casewhere a network restricts the positioning of UE.

Referring to FIG. 20, UE receives positioning restriction informationfrom a network (S2011). The positioning restriction information may beindicative of an interval in which the UE is able to performpositioning. In this example, it is assumed that the positioningrestriction information is indicative of the temporal length of thepositioning interval. The positioning restriction information may beincluded in a measurement configuration message configured by thenetwork so that the UE reports measured results, and may be thentransmitted.

When the positioning restriction information is received from thenetwork, the UE starts a restriction timer for a positioning executiontime (S2012). The UE may determine that positioning for obtaininglocation information related to measured results has been permittedwhile the restriction timer is being driven.

The UE performs measurement on a serving cell and/or at least oneneighbor cell (S2013), and performs positioning in order to obtainlocation information related to obtained measured results (S2014).

The UE sends a report message, including the measured results and thelocation information, to the network (S2015).

The UE may determine that positioning has been permitted because therestriction timer related to positioning restriction is being driveneven after sending the report message. Accordingly, the UE performsmeasurement on the serving cell and/or at least one neighbor cell(S2021), and performs positioning in order to obtain locationinformation related to obtained measured results (S2022).

The UE sends a report message, including the measured results and thelocation information, to the network (S2023).

When the restriction timer related to the positioning restrictionexpires, the UE may determine that positioning is not permitted.Accordingly, the UE stops performing the positioning (S2031).

The UE performs measurement on the serving cell and/or at least oneneighbor cell (S2032), and sends a report message including measuredresults to the network (S2033).

FIG. 21 is a flowchart illustrating another example of a report methodbased on restricted positioning according to an embodiment of thepresent invention. The example of FIG. 21 illustrates a case wherecoverage where positioning is permitted is restricted in the case wherea network restricts the positioning of UE.

Referring to FIG. 21, UE receives positioning restriction informationfrom a cell 1 (S2111). The positioning restriction information may beindicative of coverage where the UE may perform positioning. Morespecifically, a network may send the positioning restrictioninformation, including a list of cells in which the positioning of theUE is permitted, to the UE. In this example, it is assumed that thepositioning restriction information includes a cell list indicative ofthe cell 1 and a cell 2. The positioning restriction information may beincluded in a measurement configuration message configured by thenetwork so that the UE reports measured results, and may be transmitted.

The UE performs measurement on a serving cell and/or at least one cell(S2112).

The UE may determine that the execution of positioning has beenpermitted because a serving cell is now the cell 1 and the correspondingcell is a serving cell in which positioning has been permitted.Accordingly, the UE performs positioning in order to obtain locationinformation related to measured results (S2113).

The UE sends a report message, including the measured results and thelocation information, to the network (S2114).

Thereafter, the UE performs a change of the serving cell to the cell 2(S2121). The change of the serving cell of the UE may be handoverperformed in the RRC connection state or cell reselection performed inthe RRC idle state.

The UE performs measurement on the serving cell and/or at least one cell(S2122).

The UE may determine that the execution of positioning has beenpermitted because a serving cell is now the cell 2 and the correspondingcell is a serving cell in which positioning has been permitted.Accordingly, the UE performs positioning in order to obtain locationinformation related to measured results (S2123).

The UE sends a report message, including the measured results and thelocation information, to the network (S2124).

Thereafter, the UE performs a change of the serving cell to a cell 3(S2131). The change of the serving cell of the UE may be handoverperformed in the RRC connection state or cell reselection performed inthe RRC idle state.

The UE performs measurement on the serving cell and/or at least one cell(S2132).

Meanwhile, the UE may determine that the execution of positioning hasnot been permitted because the serving cell is now the cell 3 and thecorresponding cell is not a serving cell in which positioning has beenperformed. Accordingly, the UE does not perform positioning while the UEoperates using the cell 3 as a serving cell.

The UE sends a report message, including the measured results, to thenetwork (S2133).

Meanwhile, in the example described with reference to FIG. 21, the UEhas changed the serving cell through cell reselection and/or handover.In the case where positioning restriction information is included in ameasurement configuration message and provided to UE, if a serving cellis changed, a problem may occur in that information related to ameasurement configuration is no longer valid. Accordingly, there may bea need for a procedure for transferring positioning restrictioninformation from a source cell to a target cell and informing UE of thecorresponding information so that the UE operates based on the existingpositioning restriction information even after a serving cell ischanged.

Meanwhile, if positioning restriction information is included in alogged measurement configuration message for a logged MDT, whether ornot positioning restriction information according to a change of theserving cell of UE is valid is not problematic because the informationincluded in the logged measurement configuration message is valid whilethe validity timer of a logged measurement configuration is beingdriven.

FIG. 22 is a flowchart illustrating yet another example of a reportmethod based on restricted positioning according to an embodiment of thepresent invention. The example of FIG. 22 illustrates a report methodaccording to a logged MDT to which a positioning restriction scheme hasbeen applied.

Referring to FIG. 22, UE receives a logged measurement configuration,including information for performing a logged MDT, from a cell 1(S2211). The logged measurement configuration may include positioningrestriction information, and the positioning restriction information mayinclude a list of cells in which the positioning of the UE is performed.In this example, it is assumed that the positioning restrictioninformation includes a cell list indicative of the cell 1 and a cell 2.

The UE may determine that positioning is permitted while the UE operatesusing the cell 1 as a serving cell because a serving cell is the cell 1and the cell list included in the positioning restriction information isindicative of the cell 1. Accordingly, after entering an idle state, theUE performs measurement on a serving cell and/or at least one neighborcell, and performs positioning in order to obtain location informationrelated to measured results (S2212).

The UE logs the obtained measured results and location information(S2213).

When the UE (re)establishes RRC connection with the cell and enters theRRC connection state, the UE notifies the cell 1 that the loggedmeasurement to be reported is present, and may report the loggedmeasurement after receiving a report request from the cell 1.

Thereafter, the UE performs a change of the serving cell to the cell 2(S2221). The change of the serving cell of the UE may be handover thatis performed by the UE in the RRC connection state or cell reselectionthat is performed by the UE in the RRC idle state. Meanwhile, when theUE establishes RRC connection with the cell 2 and enters the RRCconnection state in the state in which the UE has not reported thelogged measurement to the cell 1, the UE notifies the cell 2 that thelogged measurement to be reported is present, and may report the loggedmeasurement after receiving a report request from the cell 2.

The UE may determine that positioning is permitted while the UE operatesusing the cell 2 as a serving cell because a serving cell is the cell 2and the cell list included in the positioning restriction information isindicative of the cell 2. Accordingly, after entering an idle state, theUE performs measurement on a serving cell and/or at least one neighborcell and performs positioning in order to obtain location informationrelated to measured results (S2222).

The UE logs the obtained measured results and location information(S2223).

When the UE (re)establishes RRC connection with the cell 2 again andenters the RRC connection state, the UE notifies the cell 2 that thereis logged measurement to be reported, and may report the loggedmeasurement after receiving a report request from the cell 2.

Thereafter, the UE performs a change of the serving cell to a cell 3(S2321). The change of the serving cell of the UE may be handover thatis performed by the UE in the RRC connection state or cell reselectionthat is performed by the UE in the RRC idle state. Meanwhile, when theUE establishes RRC connection with the cell 3 and enters the RRCconnection state in the state in which the UE has not reported thelogged measurement to the cell 1, the UE notifies the cell 3 that thelogged measurement to be reported is present, and may report the loggedmeasurement after receiving a report request from the cell 3.

The UE may determine that positioning is not permitted while the UEoperates using the cell 3 as a serving cell because a serving cell isthe cell 2 and the cell list included in the positioning restrictioninformation is not indicative of the cell 3. Accordingly, after enteringan idle state, the UE obtains measured results by performing measurementon a serving cell and/or at least one neighbor cell, but does notperform positioning (S2232). In this example, although the positioningof UE is not permitted, the UE has performed measurement and loggingbased on the logged measurement configuration. However, UE may notperform measurement and logging if positioning is not permitteddepending on a detailed implementation of an embodiment of the presentinvention. Furthermore, if whether the positioning of UE is permitted ornot is determined based on logging area restriction information for alogged measurement configuration, the execution of the positioning andthe execution of the measurement of UE may be performed at the same timeor may not be performed at the same time because they depend on eachother.

The UE logs the obtained measured results and location information(S2233).

When the UE (re)establishes RRC connection with the cell 3 again andenters the RRC connection state, the UE notifies the cell 3 that thelogged measurement to be reported is present, and may report the loggedmeasurement after receiving a report request from the cell 3.

A logged measurement configuration for a logged MDT has a position asvalid information until a validity timer related to the validity of thelogged measurement configuration expires. Accordingly, if UE hasobtained positioning restriction information through the loggedmeasurement configuration, the UE may obtain measured results and/orlocation information by performing measurement and/or positioning basedon information related to the measurement and logging, included in thelogged measurement configuration, and positioning restrictioninformation if the validity timer is driven although the UE changes aserving cell through cell reselection and/or handover. As describedabove, if positioning restriction information is indicative of apositioning restriction area, a positioning restriction scheme may bevery properly combined with a logged MDT and operated.

In accordance with an embodiment of the present invention, a network canrestrict positioning so that UE performs positioning only in a specifictime interval or specific network area. Accordingly, a network canobtain location information in the time and place in which locationinformation obtained through positioning can be more usefully used. Incontrast, a network can reduce overhead by restricting a report onlocation information in the time and area in which the importance oflocation information is relatively low. Through such selectivecollection of location information, network optimization can be moreefficiently performed, and the performance of a wireless communicationsystem can be further improved.

FIG. 23 is a block diagram illustrating a wireless apparatus in which anembodiment of the present invention is implemented. This apparatus mayimplement the operations of the UE and/or the network which performs theembodiments described with reference to FIGS. 19 to 22.

The wireless apparatus 2300 includes a processor 2310, memory 2320, anda Radio Frequency (RF) unit 2330. The processor 2310 performs theproposed functions, processes and/or methods. The processor 2310 may beimplemented to perform the measurement of radio resources and to obtainlocation information related to the measurement. The processor 2310 maybe configured to receive positioning restriction information and todetermine whether or not to perform positioning based on the positioningrestriction information. If the execution of positioning is permitted,the processor 2310 may be configured to obtain location information. Theprocessor 2310 may be configured to report measured results and/orobtained location information. The processor 2310 may be configured toimplement the embodiments of the present invention described withreference to the drawings.

The RF unit 2330 is connected to the processor 2310, and sends andreceives radio signals.

The processor 2310 and the RF unit 2330 may be implemented to send andreceive radio signals according to one or more communication standards.The RF unit 2330 may include one or more transceivers capable of sendingand receiving radio signals.

The processor may include Application-Specific Integrated Circuits(ASICs), other chipsets, logic circuits, and/or data processors. Thememory may include Read-Only Memory (ROM), Random Access Memory (RAM),flash memory, memory cards, storage media and/or other storage devices.The RF unit may include a baseband circuit for processing a radiosignal. When the above-described embodiment is implemented in software,the above-described scheme may be implemented using a module (process orfunction) which performs the above function. The module may be stored inthe memory and executed by the processor. The memory may be disposed tothe processor internally or externally and connected to the processorusing a variety of well-known means.

In the above exemplary systems, although the methods have been describedon the basis of the flowcharts using a series of the steps or blocks,the present invention is not limited to the sequence of the steps, andsome of the steps may be performed at different sequences from theremaining steps or may be performed simultaneously with the remainingsteps. Furthermore, those skilled in the art will understand that thesteps shown in the flowcharts are not exclusive and may include othersteps or one or more steps of the flowcharts may be deleted withoutaffecting the scope of the present invention.

What is claimed is:
 1. A report method by a user equipment in a wirelesscommunication system, the method comprising: receiving a loggedmeasurement configuration including configuration information for alogged Minimization Driving Test (MDT) and positioning restrictioninformation from a network; and determining whether positioning ispermitted based on the positioning restriction information, entering aRadio Resource Control (RRC) idle state when the positioning ispermitted; obtaining location information by performing the positioningin the RRC idle state; performing a measurement on a serving cell or atleast one neighbor cell based on the logged measurement configuration;and reporting the location information to the network.
 2. The reportmethod of claim 1, wherein the positioning restriction information isindicates a start time point and an end time point of a time interval inwhich the positioning of the user equipment is permitted.
 3. The reportmethod of claim 2, wherein determining whether the positioning ispermitted comprises determining whether the user equipment is operatingbetween the start time point and the end time point.
 4. The reportmethod of claim 1, wherein: the positioning restriction informationindicates a length of a time interval during which the positioning ispermitted, and the method further comprises starting a restriction timerbased on the positioning restriction information.
 5. The report methodof claim 4, wherein determining whether the positioning is permittedcomprises determining whether the restriction timer is expired.
 6. Thereport method of claim 1, wherein the positioning restrictioninformation is indicative of coverage in which the positioning ispermitted.
 7. The report method of claim 6, wherein: the coverage inwhich the positioning is permitted is at least one cell, and thepositioning restriction information comprises a cell list indicative ofthe at least one cell.
 8. The report method of claim 7, whereindetermining whether the positioning is permitted comprises determiningwhether a serving cell of the user equipment is indicated by the celllist.
 9. The report method of claim 6, wherein: the coverage in whichthe positioning is permitted is at least one frequency, and thepositioning restriction information comprises a frequency listindicative of the at least one frequency.
 10. The report method of claim9, wherein determining whether the positioning is permitted comprisesdetermining whether an operation frequency of the serving cell of theuser equipment is indicated by the frequency list.
 11. The report methodof claim 1, further comprising: logging the results of the measurementand the location information if the positioning is permitted, whereinreporting the location information to the network comprises reporting areport message, comprising the logged measured results and locationinformation, to the network.
 12. The report method of claim 11, furthercomprising: logging the results of the measurement if the positioning isnot permitted; and reporting the report message, comprising the loggedmeasured results, to the network.
 13. A wireless apparatus operating ina wireless communication system, the wireless apparatus comprises: aRadio Frequency (RF) unit that sends and receives radio signals; and aprocessor that is functionally coupled to the RF unit and operates,wherein the processor is configured to: receive a logged measurementconfiguration including configuration information for a loggedMinimization Driving Test (MDT) and positioning restriction informationfrom a network; determine whether positioning is permitted based on thepositioning restriction information, enter a Radio Resource Control(RRC) idle state when the positioning is permitted; obtain locationinformation by performing the positioning in the RRC idle state, performa measurement on a serving cell or at least one neighbor cell based onthe logged measurement configuration, and report the locationinformation to the network.